Systems and Methods for Determining Lesion Depth Using Fluorescence Imaging

ABSTRACT

Systems, catheter and methods for treating Atrial Fibrillation (AF) are provided, which are configure to illuminate a heart tissue having a lesion site; obtain a mitochondrial nicotinamide adenine dinucleotide hydrogen (NADH) fluorescence intensity from the illuminated heart tissue along a first line across the lesion site; create a 2-dimensional (2D) map of the depth of the lesion site along the first line based on the NADH fluorescence intensity; and determine a depth of the lesion site at a selected point along the first line from the 2D map, wherein a lower NADH fluorescence intensity corresponds to a greater depth in the lesion site and a higher NADH fluorescence intensity corresponds to an unablated tissue. The process may be repeated to create a 3 dimensional map of the depth of the lesion.

RELATED APPLICATIONS

This application is a continuation patent application of U.S.application Ser. No. 14/541,991, filed Nov. 14, 2014, which claims thebenefit of and priority to U.S. Provisional Application Ser. No.61/904,018, filed on Nov. 14, 2013, each of which is incorporated hereinby reference in its entirety.

FIELD

The present disclosure generally relates to medical procedures whereablation energy is applied to the body to form therapeutic lesions. Inparticular, the present disclosure relates to systems and methods forimaging lesions and tissue to determine lesion depth.

BACKGROUND

Atrial fibrillation (AF) is the most common sustained arrhythmia in theworld, which currently affects millions of people. In the United States,AF is projected to affect 10 million people by the year 2050. AF isassociated with increased mortality, morbidity, and an impaired qualityof life, and is an independent risk factor for stroke. The substantiallifetime risk of developing AF underscores the public heath burden ofthe disease, which in the U.S. alone amounts to an annual treatment costexceeding $7 billion.

Most episodes in patients with AF are known to be triggered by focalelectrical activity originating from within muscle sleeves that extendinto the Pulmonary Veins (PV). Atrial fibrillation may also be triggeredby focal activity within the superior vena cava or other atrialstructures, i.e. other cardiac tissue within the heart's conductionsystem. These focal triggers can also cause atrial tachycardia that isdriven by reentrant electrical activity (or rotors), which may thenfragment into a multitude of electrical wavelets that are characteristicof atrial fibrillation. Furthermore, prolonged AF can cause functionalterations in cardiac cell membranes and these changes furtherperpetuate atrial fibrillation.

Radiofrequency ablation (RFA), laser ablation and cryo ablation are themost common technologies of catheter-based mapping and ablation systemsused by physicians to treat atrial fibrillation. Physician uses acatheter to direct energy to either destroy focal triggers or to formelectrical isolation lines isolating the triggers from the heart'sremaining conduction system. The latter technique is commonly used inwhat is called pulmonary vein isolation (PVI). However, the success rateof the AF ablation procedure has remained relatively stagnant withestimates of recurrence to be as high as 30% to 50% one-year postprocedure. The most common reason for recurrence after catheter ablationis one or more gaps in the PVI lines. The gaps are usually the result ofineffective or incomplete lesions that may temporarily block electricalsignals during the procedure but heal over time and facilitate therecurrence of atrial fibrillation.

Therefore, there is a need in forming and verifying proper lesions,reduce fluoroscopy time, and reduce the rate of arrhythmia occurrence,thereby improving outcomes and reducing costs.

SUMMARY

According to some aspects of the present disclosure, there is provided amethod for determining a depth of a lesion site that includesilluminating a heart tissue having a lesion site; obtaining amitochondrial nicotinamide adenine dinucleotide hydrogen (NADH)fluorescence intensity from the illuminated heart tissue along a firstline across the lesion site; creating a 2-dimensional (2D) map of thedepth of the lesion site along the first line based on the NADHfluorescence intensity; and determining a depth of the lesion site at aselected point along the first line from the 2D map, wherein a lowerNADH fluorescence intensity corresponds to a greater depth in the lesionsite and a higher NADH fluorescence intensity corresponds to anunablated tissue.

In some embodiments, the method further comprises forming the lesionsite in the heart tissue by ablation. The step of obtaining may comprisedetecting the NADH fluorescence from the illuminated tissue; creating adigital image of the lesion site from the NADH fluorescence, the digitalimage comprising a plurality of pixels; and determining a NADHfluorescence intensity of the plurality of pixels along the line acrossthe lesion site. In some embodiments, the method may further includedistinguishing the lesion site and a healthy tissue in the digital imagebased on an amount of the NADH fluorescence from the lesion site and thehealthy tissue; normalizing the digital image based on the NADHfluorescence intensity of pixels representative of the healthy tissue.

In some embodiments, the step of detecting comprises filtering the NADHfluorescence through a bandpass filter of between about 435 nm and 485nm. In some embodiments, the healthy tissue has a lighter appearance andthe lesion site has a darker appearance. The step of creating maycomprise plotting the NADH fluorescence intensity along the line acrossthe lesion site to create the 2D map of depth of the lesion site.

In some embodiments, the method further includes obtaining a NADHfluorescence intensity from the illuminated heart tissue along a secondline across the lesion site; creating a 2D map of the depth of thelesion site along the second line based on the NADH fluorescenceintensity; constructing a 3-dimensional (3D) image of the lesion sitefrom the 2D map along the first line and the 2D map along the secondline. In some embodiments, the steps of obtaining, creating anddetermining may be repeated multiple times along a perpendicular lineacross a width of the lesion site, each of the 2D maps of the depthbeing parallel to the first line along the length of the lesion site;and integrating each of the respective 2D maps of the depth of thelesion site on a perpendicular line to reconstruct a 3D image of thedepth of the lesion site.

The step of determining may comprise applying a pixel gray scale rangingfrom completely black to completely white. The method may be used toanalyze epicardial tissue, endocardial tissue, atrial tissue, andventricular tissue.

In some embodiments, the illuminating step comprises illuminating theheart tissue with a laser generated UV light, wherein the lasergenerated UV light may have a wavelength of about 300 nm to about 400nm.

According to some aspects of the present disclosure, there is provided asystem for imaging heart tissue that includes an illumination deviceconfigured to illuminate a tissue having a lesion site to excitemitochondrial nicotinamide adenine dinucleotide hydrogen (NADH) in thetissue; an imaging device configured to detect NADH fluorescence fromthe illuminated tissue; and a controller in communication with theimaging device, the controller being programmed to obtain a NADHfluorescence intensity from the illuminated tissue along a first lineacross the lesion site; create a 2-dimensional (2D) map of the depth ofthe lesion site along the first line based on the NADH fluorescenceintensity; and determine a depth of the lesion site at a selected pointalong the first line from the 2D map, wherein a lower NADH fluorescenceintensity corresponds to a greater depth in the lesion site and a higherNADH fluorescence intensity corresponds to an unablated tissue.

According to some aspects of the present disclosure, there is provided asystem for imaging heart tissue that includes a catheter having a distalregion and a proximal region; a light source; an optical fiber extendingfrom the light source to the distal region of the catheter to illuminatea tissue having a lesion site in proximity to the distal end of thecatheter to excite mitochondrial nicotinamide adenine dinucleotidehydrogen (NADH) in the tissue; an image bundle for detecting a NADHfluorescence from the illuminated tissue; a camera connected to theimage bundle, the camera being configured to receive the NADHfluorescence from the illuminated tissue and to generate a digital imageof the illuminated tissue, the digital image comprising a plurality ofpixels; and a controller in communication with the camera, thecontroller being configured to determine, from the digital image, a NAHDfluorescence intensity of the plurality of pixels along a first lineacross the lesion site, create a 2D map of a depth of the lesion sitealong the first line based on the NADH fluorescence intensity, anddetermine a depth of the lesion site at a selected point along the firstline from the 2D map, wherein a lower NADH fluorescence intensitycorresponds to a greater depth in the lesion site and a higher NADHfluorescence intensity corresponds to an unablated tissue

BRIEF DESCRIPTION OF THE DRAWINGS

The presently disclosed embodiments will be further explained withreference to the attached drawings, wherein like structures are referredto by like numerals throughout the several views. The drawings shown arenot necessarily to scale, with emphasis instead generally being placedupon illustrating the principles of the presently disclosed embodiments.

FIG. 1A is a system architecture diagram of an embodiment system of thepresent disclosure.

FIG. 1B is a block diagram of an embodiment system of the presentdisclosure;

FIG. 1C is a diagram showing an exemplary computer system suitable foruse with the methods and systems of the present disclosure.

FIG. 2 is a view of a specialty catheter in accordance with anembodiment of the present disclosure.

FIG. 3 is a close-up photo of an inflated catheter balloon and tip inaccordance with an aspect of the present disclosure.

FIG. 4A is a flow diagram of a method in accordance with the presentdisclosure.

FIG. 4B is a flow diagram of a method in accordance with the presentdisclosure.

FIGS. 4C-4F show the depth analysis performed along a single line inaccordance with the present disclosure.

FIG. 4G and FIG. 4H shows the depth analysis in 3D with two ablationlesions and inter-lesion gap imaged with by fNADH, in accordance withthe present disclosure.

FIG. 5A and FIG. 5B are a side-by-side plot of the emission wavelengthsof healthy cardiac tissue (FIG. 5A) and ablated cardiac tissue (FIG.5B).

FIG. 6A and FIG. 6B is a side-by side image comparison of a cardiaclesion illuminated under white light (FIG. 6A) and the NADH fluorescencedue to illumination under UV light (FIG. 6B).

FIG. 7A is a photo of an epicardial image showing a diameter measurementof a lesion viewed under UV illumination.

FIG. 7B is a photo of a diameter measurement of the same lesion in FIG.7A, but as stained by triphenyltetrazoliun chlorate (TTC).

FIG. 7C is a plot of the correlation of a lesion size diametermeasurement of the fluoresced lesions and TTC stained lesions.

FIG. 8A is a plot of a correlation of a lesion depth to NADHfluorescence.

FIG. 8B is a photo of a diameter measurement of two lesions revealed bystaining with TTC.

FIG. 8C is a photo of a diameter measurement of fNAHD visualizedlesions.

FIG. 8D is an inverted signal of FIG. 8C.

FIG. 9 is a plot of compiled data comparing a lesion depth to invertedNADH fluorescence intensity.

FIG. 10 is a 3D reconstruction of a depth of a lesion.

FIG. 11 is a plot of NADH fluorescence intensity versus a lesion depthvarying ablation duration (time).

FIG. 12A and FIG. 12B illustrate a lesion formed by cryo ablation and a3D plot of the lesion, respectively.

FIG. 12C and FIG. 12D illustrate a lesion formed by radiofrequencyablation and a 3D plot of the lesion, respectively.

FIG. 12E and FIG. 12F illustrate three different lesions and a 3D plotshowing a physical relation of the corresponding depths of the lesions,respectively. Interlesion gap is illustrated on the 3-D reconstructionimage.

FIG. 13A is an image of a lesion formed by cryprobe.

FIG. 13B is an enlargement of the lesion of FIG. 13A.

FIG. 13C is a 3D plot of the lesion formed by cryprobe of FIG. 13A.

FIG. 14 shows a plot of an intensity of epicardial fNADH correlated inan inverse manner with an actual lesion depth as measured by TTCanalysis.

While the above-identified drawings set forth presently disclosedembodiments, other embodiments are also contemplated, as noted in thediscussion. This disclosure presents illustrative embodiments by way ofrepresentation and not limitation. Numerous other modifications andembodiments can be devised by those skilled in the art which fall withinthe scope and spirit of the principles of the presently disclosedembodiments.

DETAILED DESCRIPTION

The present disclosure generally relates to medical procedures whereradiofrequency, laser or cryo ablation energy is applied to the body toform therapeutic lesions. In particular, the present disclosure relatesto systems and methods that can image cardiac lesions and tissue usingnicotinamide adenine dinucleotide hydrogen (NADH) fluorescence (fNADH).The present systems and methods may be used during the treatment ofAtrial Fibrillation (AF). In particular, the present disclosure relatesto systems and methods for generating lesion depth maps by analyzingNADH fluorescence intensity data to determine the depth of lesions. Insome embodiments, the present systems and methods may be employed todetermine depth of lesions in heart tissue (endocardial, epicardial,atrial and ventricular tissue). However, the presently disclosed methodsand systems may also be applicable for analyzing lesions in other tissuetypes. The lesions to be analyzed may be created by ablation duringablation procedure. In some embodiments, existing lesions, created byablation or by other means, may also be analyzed using methods andsystems disclosed herein.

According to aspects of the present disclosure, the fluorescence ofendogenous NADH (fNADH) in heart tissue can be imaged in real-time toidentify ablated and unablated areas. Gaps between ablated areas can beidentified using the fNADH imaging and the gaps can then be ablated. Theimaging can be performed during the ablation procedure and does notrequire additional chemicals, such as contrast agents, tracers or dyes.

In some embodiments, the intensity of fluorescence can be measured andplotted with the lowest fluorescence (darkest) corresponding to thedeepest ablated lesions and the highest fluorescence (lightest)corresponding to the unablated or healthy tissue. Any levels of graybetween the extremes of light and dark generally correspond to thedegree of tissue lesion depth. The presently disclosed systems andmethods can be used to determine lesion depth based on the pixelintensity obtained after ablating the tissue and imaging the tissue witha fNADH system. In some embodiments, the correlated depth data can beintegrated into a 3D reconstruction of the lesion(s) giving thephysician timely feedback about lesion geometry and quality. Thus, thepresent disclosure addresses the lack of lesion-quality feedback oftoday's known technologies and methods by providing depth-of-lesioninformation to the physician at the time of the procedure. For example,having depths information can be used for subsequent diagnosis andtreatment. In performing ablation procedures, particularly pulmonaryvein isolation procedures, at least one objective, among many, is todeliver ablation lesions that are deep enough to have durable resultsand enhance the success of the procedure. During the procedure it isoptimum that the ablation lesions do not have gaps and each lesion hascovered adequate depth. This is called transmural lesions, which means,without having damage to tissue outside the heart or perforates theheart; such that, the depth information is used at the time of aprocedure by helping an operator perform better lesions that are deepenough to provide adequate results and more durable result. Further, thelesions that are produced can largely depend on the ablation tool thatis used, RFA (standard vs irrigated), cryo (catheter vs balloon) andlaser, they all produce different shape lesions. It is a challenge toovercome that the lesions produced depend on the ablation tool used,such that each ablation tool results in having a variable depth whereinsome are deeper than others. In performing ablation procedures there areno minimal depth numbers, it can depend on several factors, such as thearea being ablated, atrium is thinner than ventricle or some otherfactor. For example, a 2 mm depth may be perfect for atrial tissue butpoor for ventricular tissue, however, each patient will have differentthickness tissue and require specific attention.

As noted above, high quality and verifiable lesions can be at least someof the keys to the success of the ablation procedure and avoidance ofrecurrence. Quality lesions may be of adequate depth and cause cellnecrosis completely from the endocardial surface to the epicardialsurface of the heart (i.e. transmural) while minimizing damage to thenon-cardiac structures beyond. However, the present disclosed mappingsystems and other aspects of the systems and methods provide thefeedback on the extent of cell injury caused by the ablation as well asactually verify the integrity of a lesion. Thus, the presently disclosedembodiments, among other things, address the lack of lesion-qualityfeedback of today's known technologies by providing lesion visualizationas well as depth-of-lesion information to the physician at the time ofthe procedure.

In reference to FIG. 1A and FIG. 1B, the ablation visualization system(AVS) of the present disclosure can include a light source 130A, such asa UV laser, that is external to the body of a patient and light deviceor a light delivery fiber 130B for delivering light from the lightsource to within the body of the patient, a camera 135A with appropriatefiltering, if necessary, and an image bundle 135B connected to thecamera, and a computer system 140 having one or more displays 140A (fora technician) and 140B (for a physician) with image processing softwareon its processor or controller.

FIG. 1C shows, by way of example, a diagram of a typical processingarchitecture, which may be used in connection with the methods andsystems of the present disclosure. A computer processing device 200 canbe coupled to display 212 for graphical output. Processor 202 can be acomputer processor 204 capable of executing software. Typical examplescan be computer processors (such as Intel® or AMD® processors), ASICs,microprocessors, and the like. Processor 204 can be coupled to memory206, which can be typically a volatile RAM memory for storinginstructions and data while processor 204 executes. Processor 204 mayalso be coupled to storage device 208, which can be a non-volatilestorage medium, such as a hard drive, FLASH drive, tape drive, DVDROM,or similar device. Although not shown, computer processing device 200typically includes various forms of input and output. The I/O mayinclude network adapters, USB adapters, Bluetooth radios, mice,keyboards, touchpads, displays, touch screens, LEDs, vibration devices,speakers, microphones, sensors, or any other input or output device foruse with computer processing device 200. Processor 204 may also becoupled to other type of computer-readable media, including, but are notlimited to, an electronic, optical, magnetic, or other storage ortransmission device capable of providing a processor, such as theprocessor 204, with computer-readable instructions. Various other formsof computer-readable media can transmit or carry instructions to acomputer, including a router, private or public network, or othertransmission device or channel, both wired and wireless. Theinstructions may comprise code from any computer-programming language,including, for example, C, C++, C#, Visual Basic, Java, Python, Perl,and JavaScript.

Program 210 can be a computer program or computer readable codecontaining instructions and/or data, and can be stored on storage device208. The instructions may comprise code from any computer-programminglanguage, including, for example, C, C++, C#, Visual Basic, Java,Python, Perl, and JavaScript. In a typical scenario, processor 204 mayload some or all of the instructions and/or data of program 210 intomemory 206 for execution. Program 210 can be any computer program orprocess including, but not limited to web browser 166, browserapplication 164, address registration process 156, application 142, orany other computer application or process. Program 210 may includevarious instructions and subroutines, which, when loaded into memory 206and executed by processor 204 cause processor 204 to perform variousoperations, some or all of which may effectuate the methods for managingmedical care disclosed herein. Program 210 may be stored on any type ofnon-transitory computer readable medium, such as, without limitation,hard drive, removable drive, CD, DVD or any other type ofcomputer-readable media.

It is possible the light source 130A may include a cart 132. In someembodiments, the system may further include a specialty catheter 105Acomprising an inflatable balloon 105B. In some embodiments, the imagebundle 135B and the light delivery fiber may extend from the outside ofthe catheter to a distal region of the catheter inside the balloon 105B.It is contemplated that there could be multiple components of eachcomponent added to the above disclosed system. The system may furtherinclude a guidewire for the catheter 105C, a EP Fluoroscopy System 160,a sterable sheath 165A, a guidewire for steerable sheath 165B, anintroducer sheath kit 165C, an indeflator 170 and a trasseptal kit 180.

FIG. 1B is a block diagram of an exemplary system in accordance with thepresent disclosure. The AVS system includes external equipment 125having a light source 130A, a camera 135A with appropriate filtering, ifnecessary, and a computer system (not shown) having one or more displays140A with image processing software. The AVS system includes internalequipment including an ablation device 140, an illumination device 130Band an imaging device 135B, wherein the internal components are withinan internal balloon 105B associated with a catheter 105A. It is notedthat the internal equipment including the catheter 105A with aninflatable balloon catheter 105B is coupled to external equipment 125.In some embodiments, the illumination device 130B and an imaging device135B may utilize a fiber-optic waveguide to pass the light to and fromthe treated tissue.

Still referring to FIG. 1A and FIG. 1B, the light source 130A mayinclude a laser that is the source for illumination of the myocardium.The output wavelength of the laser may be within the target fluorophore(NADH, in this case) absorption range in order to induce fluorescence inthe healthy myocardial cells. In some embodiments, the laser can be a UVlaser.

According to some aspects of FIG. 1A and FIG. 1B, a laser generated UVlight may provide much more power for illumination and its wavelengthcan be pure at whatever number of nanometers that may be required.Emittance of more than one wavelength may be problematic in that theymay cause other molecules to fluoresce (other than NADH) and they maycause reflection in the reflectance range injecting image noise orworse, drowning out the NADH reflectance signal. There are sources ofcommercial lasers that can emit in a desired illumination band and theyare available in many power settings near 50 to 200 mW and higher. Theinstant system, in some embodiments, uses a laser with adjustable powerup to 150 mW.

The wavelength range on the illumination source may be bounded by theanatomy of interest, specifically choosing a wavelength that causesmaximum NADH fluorescence but not too much collagen fluorescence, whichis activated by only slightly longer wavelengths. In some embodiments,the laser has a wavelength from 300 nm to 400 nm. In some embodiments,the laser has a wavelength from 330 nm to 370 nm. In some embodiments,the laser has a wavelength from 330 nm to 355 nm. In some embodiments,355 nm may be used because it was near the peak of NADH excitation andjust below collagen excitation. The output power of the laser may behigh enough to produce a recoverable fluorescence data, yet not so highas to induce cellular damage.

Still referring to FIG. 1A and FIG. 1B, the catheter 105A can beemployed to perform many functions including, without limitations,vascular navigation, blood displacement, propagation of light from thelight source 130A to the myocardium, and image gathering of thefluorescence light. One example of a suitable catheter is disclosed injointly-owned U.S. application Ser. No. 13/624,902, which isincorporated herein in its entirety. In some embodiments, the ablationtechnology is housed with or incorporated within the system and catheterembodiment.

In reference to FIG. 2 and FIG. 3, the catheter 105A may include aballoon 105B at or near the distal end of the catheter 105A. Since bloodabsorbs the illumination and fluorescence wavelengths, the balloon 105Bmay displace blood from the myocardial surface. To do so, the balloon105B may be expandable and compliant to seat well within theanatomy—especially the pulmonary veins. The medium used to inflate theballoon 105B may also be optically transparent and yet ideally befluoroscopically opaque for navigation purposes. Suitable inflationmedium include, but are not limited to, Deuterium (heavy water) and CO₂,which meet both requirements. The balloon 105B may also be constructedof a material that is optically clear in at least the wavelengths ofconcern for both illumination of the myocardium and fluorescence. Theballoon 105B may be either, made of non-compliant materials but withoptimally variable sizes of best fit into pulmonary veins and otherstructures, or, made of a compliant material such as silicone orurethane. In some embodiments, the balloon 105B may be opticallytransparent in the UV range of 330 nm to 370 nm.

In some embodiments, the balloon 105B is optically clear from 330 nm to370 nm for UV illumination and from 400 nm to 500 nm for thefluorescence wavelengths. Suitable UV-transparent materials for theballoon include, but are not limited to, silicone and urethane.

Still referring to FIG. 2 and FIG. 3, the catheter 105A may also be usedto efficiently deliver the illuminating light, such as UV laser lightand optionally white light, from the external light source to theballoon 105B and out of the balloon 105B to the myocardium. In someembodiments, a laser delivery fiber, usually made of quartz due to itsUV efficiency and small diameter, may be used to deliver illuminatinglight from a UV laser light source.

The catheter of FIG. 2 and FIG. 3 may also be employed to collect andtransfer the NADH fluorescence light from the illuminated tissue to anexternal camera (see FIG. 1A and FIG. 1B). In some embodiments, this maybe accomplished via an imaging fiber bundle (see FIG. 1A) extending fromthe distal region of the catheter to the external camera. In someembodiments, the image bundle may include one or more of individual,single-mode fibers that together maintain image integrity whiletransporting it along the length of the catheter to a camera and afilter, as necessary. The imaging bundle, though flexible and small indiameter, may be able to achieve a sufficient field of view for imagingthe target tissue area covered by the balloon.

The camera, can be connected to the computer system (see FIG. 1A) forviewing, and may have high quantum efficiency for wavelengthscorresponding to NADH fluorescence. One such camera is an Andor iXonDV860. An optical bandpass filter of between 435 nm and 485 nm, in someembodiments, of 460 nm, may be inserted between the imaging bundle andthe camera to block light outside of the NADH fluorescence emissionband. In some embodiments, other optical bandpass filters may beinserted between the imaging bundle and the camera to block lightoutside of the NADH fluorescence emission band selected according to thepeak fluorescence of the tissue being imaged.

In some embodiments, the digital image that is produced by the camera isused to do the 2D and 3D reconstruction. In some embodiments, the imagebundle may be connected to the camera, the camera may generate a digitalimage from NADH fluorescence (fNADH), which can be displayed on thecomputer. The computer processor/controller has the data of pixelintensity for pixels forming the digital image, so the computerprocessor/controller may use the 2D or 3D program(s) to generate thedepth correlation plots. In some embodiments, the NADH fluorescence maybe conveyed directly to the computer processor/controller.

In reference to FIG. 4A, operation of the systems of the presentdisclosure is illustrated. Initially, (step 410) the catheter isinserted into the area of heart tissue affected by the atrialfibrillation, such as the pulmonary vein/left atrial junction or anotherarea of the heart. Blood is removed from the visual filed, for example,by the balloon. For atrial fibrillation ablation a transparent balloonsurrounding the fiber optic waveguide can be used to displace the bloodat the pulmonary vein/left atrial junction. The affected area may beilluminated by ultra-violet light from the light source and the opticalfiber or another illumination device (step 415). Tissue in theilluminated area may be ablated using an ablation device (step 420),either before or after illumination. Either point-to-point RF ablationor cryoablation or laser or other known ablation procedures may beemployed using the systems of the present disclosure. Ablation proceedsby threading the tip through the central lumen of the catheter oroutside the catheter. After the procedure, the ablation tip may beretracted. In some embodiments, an ablation tip may be incorporated intothe catheters disclosed herein.

Still referring to FIG. 4A, the illuminated area is imaged by thecombination of the imaging bundle and camera (step 425). In someembodiments, the methods of the present disclosure rely on imaging ofthe fluorescence emission of NADH, which is a reduced form ofnicotinamide adenine dinucleotide (NAD+). NAD+ is a coenzyme that playsimportant roles in the aerobic metabolic redox reactions of all livingcells. It acts as an oxidizing agent by accepting electrons from citricacid cycle (tricarboxylic acid cycle), which occurs in themitochondrion. By this process, NAD+ is thus reduced to NADH. NADH andNAD+ are most abundant in the respiratory unit of the cell, themitochondria, but are also present in the cytoplasm. NADH is an electronand proton donor in mitochondria to regulate the metabolism of the celland to participate in many biological processes including DNA repair andtranscription.

By measuring the UV-induced fluorescence of tissue, it is possible tolearn about the biochemical state of the tissue. NADH fluorescence hasbeen studied for its use in monitoring cell metabolic activities andcell death. Several studies in vitro and in vivo investigated thepotential of using NADH fluorescence intensity as an intrinsic biomarkerof cell death (either apoptosis or necrosis) monitoring. Once NADH isreleased from the mitochondria of damaged cells or converted to itsoxidized form (NAD+), its fluorescence markedly declines, thus making itvery useful in the differentiation of a healthy tissue from a damagedtissue. NADH can accumulate in the cell during ischemic states whenoxygen is not available, increasing the fluorescent intensity. However,NADH presence disappears all together in the case of a dead cell. Thefollowing table summarizes the different states of relative intensitydue to NADH fluorescence:

Relative Changes of Auto- Cellular State NADH Presence fluorescenseintensity Metabolically Active Normal Baseline Metabolically Active butIncreased to Increased Impaired (Ischemia) Hypoxia MetabolicallyInactive None Full Attenuation (Necrotic)

Still referring to FIG. 4A, while both NAD+ and NADH absorb UV lightquite readily, NADH is autofluorescent in response to UV excitationwhereas NAD+ is not. NADH has a UV excitation peak of about 350-360 nmand an emission peak of about 460 nm. In some embodiments, the methodsof the present disclosure may employ excitation wavelengths betweenabout 330 to about 370 nm. With the proper instrumentation, it is thuspossible to image the emission wavelengths as a real-time measure ofhypoxia as well as necrotic tissue within a region of interest.Furthermore, a relative metric can be realized with a grayscalerendering proportionate to NADH fluorescence.

Under hypoxic conditions, the oxygen levels decline. The subsequentfNADH emission signal may increase in intensity indicating an excess ofmitochondrial NADH. If hypoxia is left unchecked, full attenuation ofthe signal will ultimately occur as the affected cells along with theirmitochondria die. High contrast in NADH levels may be used to identifythe perimeter of terminally damaged ablated tissue.

Still referring to FIG. 4A, to initiate fluorescence imaging, theoperator may deploy the balloon, which is installed around the distalportion of the catheter. Next, NADH is excited by the UV light from thelight source, such as a UV laser. NADH in the tissue specimen absorbsthe excitation wavelengths of light and emits longer wavelengths oflight. The emission light may be collected and passed back to thecamera, and a display of the imaged illuminated area may be produced ona display (step 430), which is used to identify the ablated andunablated tissue in the imaged area using NADH florescence (step 435).The process may then be repeated by returning to the ablation step, ifnecessary to ablate additional tissue. It should be recognized thatalthough FIG. 4A illustrates the steps being performed sequentially;many of the steps many be performed simultaneously or nearlysimultaneously, or in a different order than shown in FIG. 4A. Forexample, the ablation, imaging and display can occur at the same time,and the identification of the ablated and unablated tissue can occurwhile ablating the tissue.

The application software, executing on the computer system by theprocessor or computer, can provide the user with an interface to thephysician. Some of the main functions can include: a laser control, acamera control, an image capture, an image conditioning (brightness andcontrast adjustment, etc.), a lesion identification, a lesion depthanalysis, a procedure event recording, and a file manipulation(creation, editing, deleting, etc.).

FIG. 4B illustrates a flow chart of the determining the lesion depthprocess. Step 440 discloses identifying ablated and unablated tissue inthe imaged area using NADH florescence via application software fromcomputer display. Step 445 discloses identifying an image or images ofinterest specific to a lesion or lesions to begin the lesion depthanalysis. Step 450 discloses identifying an area of healthy tissuewithin the image of lesion of interest. By way of a non-limitingexample, referring to FIG. 6A and FIG. 6B, imaging fluorescence of NADHin the heart can produce a display of the physiology of the lesion sitehaving a dark appearance due to lack of fluorescence, gaps having lightappearance due to normal fluorescence, and any ischemic tissue having abrighter halo type appearance surrounding the lesion site (see FIG. 6Aand FIG. 6B). Once the lesion or lesions are identified, they areselected for lesion depth analysis.

Step 455 discloses normalizing the entire image using a ratio of NADHfluorescence intensity observed at each pixel to that observed in theidentified healthy tissue. Step 460 discloses processing the resultingnormalized image data via an algorithm derived from a pre-establisheddataset correlating normalized intensity ratio to lesion depth. Lesiondepth can be computed using the ratio of healthy tissue fluorescence tolesion tissue fluorescence. First, the user identifies an area ofhealthy tissue within an image. The application software then normalizesthe entire image using the ratio of NADH fluorescence intensity observedat each pixel to that observed in the identified healthy tissue. Theresulting normalized image data is then processed via an algorithmderived from a pre-established dataset correlating normalized intensityratio to lesion depth. By using the patient's own myocardial NADHfluorescence as a control, this method drastically reduces the impact ofpatient-to-patient variations in absolute NADH fluorescence, as well asoptical losses in the illumination and imaging systems and opticalintensity variations resulting from specular and diffuse reflections,and other optical non-idealities.

Step 465 discloses the depth analysis performed along a single lineacross the lesion is completed. It is also possible that this can bedone for just one single location in the lesions from information from asingle location, a line or a region. FIGS. 4C-4F show the depth analysisperformed along a single line. For example, FIG. 4C shows an image acanine heart that has been ablated six times. The square encases asingle ablation lesion. FIG. 4D shows in the top right is an NADHfluorescence (fNADH) image obtained from the same area of a bloodperfused canine heart. FIG. 4E is a 2d depth map performed along asingle line and generated based on the digital image in FIG. 4D, thatis, from the intensity of pixels forming the digital image. FIG. 4F is ahematoxylin and eosin stained canine heart tissue cut along the sameline, which illustrates the actual depth of the lesion (the squareillustrates the border of the lesion), with the deepest areacorresponding to the darkest spot in FIG. 4D and the lowest fNADH inFIG. 4E.

Step 470 discloses repeating steps 460 to 470 along different linesparallel to the initial line, so the depth data of each line compilesinto a 3D reconstruction model of the lesion site(s). The depth analysisprocess performed along a single line across the lesion could berepeated as many times as needed along different lines parallel to theinitial line, and the depth data of each line could be compiled into a3D reconstruction model of the lesion site.

By way of a non-limiting example, FIG. 4G shows a digital image of twoablation lesions and inter-lesion gap imaged with by fNADH. FIG. 4Hshows a 3D reconstruction from pixel intensity in the digital image ofFIG. 4G. Both the 2D data and the 3D data may be used for furtherdiagnosis or treatment, as described above.

The intensity of fluorescence detected by the camera can be measured andplotted with the lowest fluorescence (darkest) corresponding to thedeepest lesions and the highest fluorescence (lightest) corresponding tothe unablated or healthy tissue. Any levels of gray between the extremesof light and dark generally correspond to the degree of tissue lesiondepth. The sensitivity of the camera sensor determines the number oflevels of gray between completely black and completely white. A fewbinary numbers are common in such applications including 256-level and65,536-level, corresponding to 8-bit and 16-bit resolution,respectively. In the case of 8-bit sensitivity, 0 would be completelyblack and 255 completely white, with 254 levels of gray in between.Using this gray-scale image, a suitable depth map can be estimated. Insome embodiments, 24 bit resolution may also be used.

It is noted that fNADH imaging can reliably and reproducibly predictcardiac ablation lesion diameter and depth. The loss of fNADH intensitycorrelated with actual measured diameter and depth of multiple RFlesions with a correlation coefficient of greater 96% and 79%,respectively. It is possible that the loss of correlation at lesiondepths greater than 2 mm occurred due to the inability of UVillumination to reliably penetrate cardiac tissue below this depth. Withfurther lesion depth, no further fNADH could be detected and areproducible plateau in fNADH signal intensity was thus observed atlesion depths of about 2 mm. The mean left atrial wall thickness atlocations in the left atrium that are often targeted for ablation is1.85 mm as measured by CT scans. Therefore, the observed nadir andplateau of fNADH signal intensity across an RF lesion serves as aplausible model for a clear, all-or-none determination of sufficientlesion depth.

The methods, systems and devices disclosed herein can be used for avariety of therapeutic procedures. Exemplary procedures in which themethods, systems and devices disclosed herein can be utilized include,but not limited to, for diagnostic and therapeutic procedures in theheart, for treating arrhythmias, such as, for example, supraventriculararrhythmias and ventricular arrhythmias, for treating atrialfibrillation, and pulmonary vein mapping and ablation. The ablatedtissue may be cardiac muscle (epicardial or endocardial heart muscle),but the methods disclosed herein should have the same effect on skeletalmuscle, liver, kidney, and other tissues with significant presence ofNADH-rich mitochondria.

The presently disclosed methods can be used with two dimensional (2D) tothree dimensional (3D) mapping protocols. A plurality of 2D images canbe superimposed onto a 3D reconstruction image of the tissue or organs,including the heart. Many arrhythmia procedures include the use ofreconstructed three dimension images of the patient's specific anatomyduring the procedure. Using a variety of imaging modalities includingcomputed tomography (CT), magnetic resonance imaging (MRI), ultrasound,and electroanatomical mapping using systems such as NAVX and CARTO. Inall cases, the three dimensional anatomical images or surfaces presentpatient specific anatomy to help target areas of tissue to treat. In allcases, the ability to visualize the precise location where lesions areformed and the precise locations where lesions are missing, e.g., the“gaps” or breaks in the lesion set, would guide the procedure tooptimize the therapeutic outcome. 2D image to 3D image mapping allowsthe system to superimpose, spatially register, and/or texture map singleor multiple images of tissue (that may indicate presence or absence oflesions) with the specific anatomy of the patient in a threedimensional, rotatable, interactive virtual environment.

In some embodiments, the systems and methods of the present disclosureallow the registration and/or overlay of the images produced by thesystem onto the specific anatomy of the patient as seen using otherimaging modalities such as an MRI image, computed tomography (CT) image,ultrasound image and three dimensional reconstructions thereof. In someembodiments, the systems and methods of the present disclosure mayfurther include the registration and/or overlay of the images producedby the system onto the specific anatomy of the patient as seen usingother electroanatomical mapping, anatomical reconstruction, andnavigational systems such as NAVX and CARTO. The registration andoverlay may be performed during the procedure in real time. Texturemapping NADH images onto reconstructed endocardial surfaces permitsvisualization of the treatment site. For example, multiple NADHsnapshots of lesions could create a full panoramic image of the entirepulmonary vein opening, or multiple pulmonary veins. Positioning sensorson the catheter tip could provide information that will allow the NADHimages to be combined together to create a 3D reconstruction image.

Examples of using the systems and methods of the present disclosure areprovided below. These examples are merely representative and should notbe used to limit the scope of the present disclosure. A large variety ofalternative designs exists for the methods and devices disclosed herein.The selected examples are therefore used mostly to demonstrate theprinciples of the devices and methods disclosed herein.

Examples

Experiments were conducted with a functionally equivalent system toproduce ablated lesions and lesion images in order to develop methods oflesion depth analysis. The experiment set is described below.

NADH Fluorescence System provided that the epicardial surface wasilluminated using an LED spotlight with a peak wavelength of 365 nm(PLS-0365-030-07-S, Mightex Systems). Emitted light was bandpassfiltered at 460 nm+/−25 nm and imaged using a CCD camera (Andor IxonDV860) fitted with a low magnification lens. The fluorescence of NADH(fNADH) was imaged to monitor the state of epicardial tissue.

The RFA System provided that RFA was performed with a standard clinicalRF generator (EPT 1000 ablation system by Boston Scientific). Thegenerator was electrically interfaced to the animal via a 4 mm cooledBlazer ablation catheter (Boston Scientific) in order to deliverlesions. A grounding pad was used at the time of ablation. The generatorwas set to temperature control mode. Cryoablation were performed usingcustom-made metal probe dipped in liquid nitrogen or by using FreezorMAX Cardiac CryoAblation Catheter by Medtronic.

Referring to FIG. 5A and FIG. 5B, first, baseline data were obtained forthe NADH excitation and emission spectrum in healthy cardiac tissue.FIG. 5A and FIG. 5B show the tissue excitation—emission matrices. Due tothe presence of NADH, healthy tissue emits strongly between 450 nm and470 nm when excited in the range of 330 nm to 370 nm. The large peakassociated with NADH is absent in ablated tissue.

An example of a typical RFA lesion is shown in FIG. 6A and FIG. 6B. Theimage on the left is captured using white light illumination while the fNADH image on the right is captured using UV excitation with a 460 nmfilter.

All animal protocols were reviewed and approved by the Animal Care andUse Committee at George Washington University School of Medicine andconformed to the guidelines on animal research.

Ex vivo experiments were initially conducted using excised, blood-freehearts of a rat (200-300 g Sprague-Dawley). The animals were heparinizedand anesthetized using standard procedures. The chest was opened using amidline incision. Hearts were then excised; the aorta was cannulated andLangendorff-perfused at constant pressure. The hearts were placed on topof a grounding pad and submerged in 37 degree Celsius Tyrode solutionduring RFA ablation. Alternatively cryoprobe was applied directly to theepicardial surface.

Radiofrequency energy was applied to the epicardium of excised,blood-free rat ventricles while varying temperature and duration togenerate RFA lesions of different sizes. A uniform contact force of 2grams as measured by a calibrated balance. Lesions of different sizeswere generated by varying the temperature (50, 60 and 70 Celsius) andtime (10, 20, 30, 40, 50 seconds) of RF applications. A total of twelveRFA lesions were generated on six different rat heart specimens.

NADH fluorescence of lesions and surrounding tissue was measured byilluminating the epicardial surface with UV light at 365 nm using aMightex Precision LED spotlight. Light corresponding to fNADH wasselected using a 460/25 nm bandpass filter and imaged using ahigh-sensitivity charge-coupled device camera. Lesions were additionallyimaged with bright light adjacent to a tape measure to allow formeasurement of the size of lesions. fNADH images were then imported intoImageJ software to measure the size and analyse the darkness profile ofeach lesion. Darkness profile was assessed by placing a linear region ofinterest (ROI) through the center of each fNADH imaged ablation lesionto measure pixel intensity at each point across the lesion periphery.Ventricular tissue was then retrograde-perfused with Tyrode solutioncontaining Triphenyltetrazolium chloride (TTC) to assess for tissuenecrosis. Epicardial lesions were excised for gross and histologicmeasurement of tissue injury.

In vivo experiments were conducted using canine open-chest models. Theanimals underwent open-chest surgery after induction of generalanesthesia. Using a 4 mm radiofrequency ablation catheter, multiplelesions were given to the epicardial surface at various durations andtemperatures. The epicardial surface of the heart was then illuminatedwith a UV light at 365 nm (Mightex precision LED spot light) and thecorresponding fNADH was passed via a 460/25 nm filter coupled to a highquantum efficient fluorescence camera (Andor Ixon DV860 camera). Thelesions were imaged under bright white light with a tape to measure thesize of the lesions.

Postmortem Examination provided that after the rat experiments, theanimal hearts were stained with TTC. TTC is a standard procedure forassessing acute nectosis, which relies on the ability of dehydrogenaseenzymes and NADH to react with tetrazolium salts to form a formazanpigment. Metabolically active tissue appeared crimson while necrotictissue appeared white. After TTC staining, the lesions were bisected atthe central linear ROI as defined prior for pixel intensity analysis forthe measurement of lesion depth across the corresponding ROI. Lesionmorphology, width, length and depth were determined and recorded atgross examination.

For the canine experiment, sections of multiple epicardial lesions werebisected longitudinally and submitted for histological staining(hematoxylin-eosin). Specimens were then analyzed under light microscopyat 40× to characterize the morphological changes for determination ofthe degree of heat-induced cell damage and necrosis.

The statistical analysis included that two independent readers measuredlesion size by fNADH and TTC stain with means and standard deviationsrecorded. Correlation coefficients of lesion size by fNADH and by TTCstain were also obtained and recorded.

The results includes that the Epicardial fNADH was first correlated tolesion size. In the rat model, a total of 12 epicardial surface lesionswere delivered and measured by two independent readers using fNADH andtriphenyltetrazolium chloride (TTC) stain (see FIG. 7A, FIG. 7B, andFIG. 7C). A typical fNADH image is illustrated in FIG. 7A, and theactual lesion diameter measurement using TTC stain is shown in FIG. 7B.Linear measure of lesion diameter using TTC (top image, 7A) correlatedwith lesion diameter obtained from the corresponding fNADH image (bottomimage, 7B). FIG. 7C shows a summary graph of lesion size vs. ablationdelivery times. For all lesion sizes, epicardial fNADH closely predictedthe actual lesion diameter as determined by TTC staining. Average NADHand TTC diameter was 7.9±1.85 mm and 8.2±1.95 mm, respectively with acorrelation coefficient of 96%.

Temperature and lesion delivery times were varied to obtain a multitudeof epicardial surface lesions at varying depths in rat hearts. Theintensity of epicardial fNADH was then measured multiple times along thecenterline of the lesions. An example lesion set is shown on FIG. 8A,FIG. 8B, FIG. 8C, and FIG. 8D with the fNADH graphed in the top panel(FIG. 8A) for the line across lesion #1 in FIG. 8C. FIG. 8B shows themeasured depth obtained from the TTC stained heart across the samelesion. FIG. 8D shows the inverted image of fNADH used in the graph(FIG. 8A). This was done so that higher intensities of inverted fNADHwould correlate with the depth of lesions shown and have a similarshape.

Referring to FIG. 9 and FIG. 10, the lesion depth was compared to theinverted fNADH signal intensity that was compiled and plotted in FIG. 9.Additionally, lesions were delivered for 10, 20, 30, 40 and 50 secondsrespectively at 50 degrees Celsius. The same comparisons were obtainedat varying temperatures and showed similar findings (see FIG. 9 and FIG.10).

Referring to FIG. 11, a linear correlation coefficient was obtained fordifferent duration times at a specified temperature using lesions madeby varying temperature and lesion duration. FIG. 11 shows the results at60 degrees Celsius with correlation coefficients ranging from 0.84 to0.97 depending on the duration of ablation.

3D reconstruction of lesion depth was obtained from canine epicardialimages by gathering gray scale from individual maps of fNADH using only5 parallel lines across the lesion and plotting values using a 3Dgraphing program.

FIG. 12A and FIG. 12B, FIG. 12C and FIG. 12D, and FIG. 12E and FIG. 12Fshow higher resolution 3D reconstructions of a cryolesion, aradiofrequency lesion, and multiple cryolesions, respectively. Of noteare the variations in lesion depth visible in the plot displayingmultiple lesions.

The experimental results validate fNADH as an accurate measure ofepicardial lesion size and as a predictor of lesion depth. 3Dreconstruction of depth is possible by repeating the methods describedabove along multiple lines through the ablation image and compiling theresults (see FIG. 10, FIG. 12A, FIG. 12B, and FIG. 12C).

FIG. 13A shows an fNADH image of an ablated lesion created by using acryo ablation catheter, for example, and FIG. 13B is a magnified imageof the same, as noted above. FIG. 13C shows the 3D depth reconstructioncorrelation plot of that same ablated lesion. The main difference isthat FIG. 12 includes some ablation lesions created with RFA, whereinRFA and cryo lesions have a different appearance in 3D.

Referring to FIG. 14, the RFA lesions were detectable anddistinguishable from viable tissue with excellent resolution since theyexhibited very low or non-detectable fNADH as compared to thesurrounding, healthier myocardium. Lesion diameter, as imaged by fNADH,closely correlated to measured lesion size by TTC (average NADH and TTCdiameter 7.9±1.85 mm and 8.2±1.95 mm, respectively; correlationcoefficient [CC] 96%). The intensity of epicardial fNADH correlated inan inverse manner with actual lesion depth as measured by TTC analysis.This relationship was reproduced with a CC of over 79% for all RFAvariables up to a lesion depth of 1.8 mm (significance p<0.0001) beyondwhich the fNADH signal intensity became saturated and plateaued, asshown in FIG. 14.

Relationship of lesion depth to epicardial fNADH was reproducible withstatistical significance. Multiple lesions of different size weregenerated on the epicardium of rat ventricles by varying RF duration andtemperature. Analysis of lesion depth to inverse fNADH signal intensitywas performed on these multiple lesions. Loss of fNADH intensitycorrelated with lesion depth with Pearson's correlation coefficient of78% and was highly significant (p<0.0001) up to a lesion depth of about2 mm. Beyond 2 mm, the relationship lost its significance as fNADHvalues plateaued.

In some embodiments, a system to image ablated and unablated tissuecomprises an ultra-violet (UV) laser light source; an inflatable ballooncatheter, containing a UV laser guide, and an image guide; an externalfluorescence camera, coupled to the catheter; a computer with display,coupled to the camera; and imaging software.

In some embodiments, the catheter further comprises a guide wire portfor catheter navigation; and/or ablation therapy technology, includingradiofrequency electrodes, laser ablation capability, or cryoablationcapability. In some embodiments, the balloon may be made of a compliantmaterial such as silicone or urethane; optically transparent in the UVrange of 330 nm to 370 nm; or optically transparent in the fluorescencelight range of 430 nm to 490 nm.

In some embodiments, method of estimating lesion depth may include thesteps of acquiring and displaying a nicotinamide adenine dinucleotidehydrogen (NADH) fluorescence data of the tissue; identifying of an areaof healthy tissue within the image; normalizing the entire image usingthe ratio of NADH fluorescence intensity observed at each pixel of theimage to that observed in the identified healthy tissue; identifying anarea or areas of ablated tissue; and applying an algorithm forcorrelating the resulting normalized image to lesion depth.

In some embodiments, the correlation algorithm uses data is then apre-established dataset correlating normalized intensity ratio to lesiondepth. In some embodiments, the lesion depth estimate uses the patient'sown myocardial NADH fluorescence as a control. In some embodiments, theablation is performed by using one or more of the followingtechnologies: radiofrequency ablation, laser ablation, or cryoablation.The tissue may be cardiac tissue. In some embodiments, a cross-sectionalplot of estimated lesion depth is made along a line indicated by theuser. In some embodiments, a 3D plot of estimated lesion depth is madeby compiling a series of cross-sectional plots.

In some embodiments, a method of treating atrial fibrillation, themethod comprises acquiring and displaying an NADH fluorescence data in acertain area of cardiac tissue, such as the ostium of a pulmonary vein;analyzing lesion depth across the image; identification of healthycardiac tissue; identification of proper lesions; identification ofincomplete lesions, if any; identification of ischemic zones (injuredbut not necrosed tissue), if any; re-apply ablation therapy whereneeded, either to fill in identified gaps in lesion lines, or tocomplete incomplete lesions, or bridge ischemic zones; repeating theabove steps, as needed to re-acquire and display the repaired tissue;and repeating the above steps to other areas of the heart, such as theremaining pulmonary veins, other parts of the left atrium, or evenspecific areas of the right atrium including the superior vena cava.

In some embodiments, a catheter to image ablated endocardial heartmuscle tissue, unablated gaps at the pulmonary vein/left atrialjunction, and lesion depth having a proximal and distal end comprises aninflatable transparent compliant or non-compliant balloon made of UVtransparent material inflated with transparent fluid capable oftransmitting light used for displacing surrounding blood to allowvisualization of NADH fluorescence at the distal end; an ultra-violetillumination device for exciting mitochondrial NADH of the pulmonaryvein and left atrial tissue using UV light transmittable fibers at thedistal end; a micro fiberscope for detecting NADH fluorescence from theilluminated pulmonary vein and left atrial tissue at the distal end; afluorescence camera at the proximal end for creating an image from thedetected NADH fluorescence, coupled to the micro fiberscope, thatincludes a 460 nm+/−25 nm band-pass filter to detect the NADHfluorescence from the illuminated pulmonary vein and left atrial tissuecaptured by the micro fiberscope, wherein the detected fluorescence datashows the physiology of the lesion site having a dark appearance due tolack of fluorescence, gaps having a light appearance due to normalfluorescence, and any ischemic tissue having a brighter halo typeappearance surrounding the lesion site; and a module for determining thedepth of the lesion site along a line across the length of the lesionsite by plotting the detected fluorescence intensity along the line;wherein a lowest fluorescence intensity measurement corresponds to thedeepest point of an lesion site and the highest fluorescence correspondsto unablated tissue.

In some embodiments, the module applies a pixel gray scale ranging fromcompletely black to completely white, where 0 is completely black and isthe deepest point and 255 is completely white and is the shallowestpoint, providing 256 (0-255) levels of gray, to create a 2D map of thedepth of the lesion site along the line, wherein the 2D map of the depthof ablated tissue is an absolute measurement, with the fNADH signalintensity is normalized to a previously established fNADH/depth greyvalue scale.

In some embodiments, the 2D map of the depth of the ablated tissue isrepeated multiple times along a perpendicular line across the width ofthe lesion site each of the 2D map of depth being parallel to the linealong the length of the lesion and integrating each of the respective 2Dmaps of depth of the ablated tissue on the perpendicular linereconstructing a 3D image of the depth of the ablated tissue.

In some embodiments, the catheter further comprises a guide wire lumento insert a flexible guide-wire. The camera may be a CCD camera withhigh quantum efficiency. In some embodiments, the micro fiberscope is anoptical imaging bundle. In some embodiments, the UV illumination isprovided by a laser source at between 330 and 370 nm, and moreparticularly at 355 nm. In some embodiments, the UV illumination fiberstip is covered with a diverging lens to refract and spread the UV light.

In some embodiments, a method for acquiring a real time image of ablatedendocardial heart muscle tissue, unablated gaps at the pulmonary veinand left atrial junction and lesion depth, comprises an inflatabletransparent compliant balloon made of UV transparent material inflatedwith transparent fluid capable of transmitting light used for displacingsurrounding blood to allow visualization of NADH fluorescence at thedistal end; illuminating with a ultra-violet light for excitingmitochondrial NADH of the pulmonary vein and left atrial tissue;detecting NADH fluorescence from the illuminated pulmonary vein and leftatrial tissue using optical imaging bundle; creating an image with afluorescence camera by filtering the detected NADH fluorescence with 460nm band-pass filter; wherein the detected fluorescence data shows thephysiology of the lesion site having a dark appearance due to lack offluorescence, gaps having a light appearance due to normal fluorescence,and any ischemic tissue having a brighter halo type appearancesurrounding the lesion site; and a module for determining the depth ofthe lesion site along a line across the length of the lesion site byplotting the detected fluorescence intensity along the line; wherein alowest fluorescence intensity measurement corresponds to the deepestpoint of an lesion site and the highest fluorescence corresponds tounablated tissue. In some embodimetns, the module applies a pixel grayscale ranging from completely black to completely white, where 0 iscompletely black and is the deepest point and 255 is completely whiteand is the shallowest point, providing 256 (0-255) levels of gray, tocreate a 2D map of the depth of the lesion site along the line, whereinthe 2D map of the depth of ablated tissue is an absolute measurement,with the fNADH signal intensity is normalized to a previouslyestablished fNADH/depth grey value scale. In some embodiments, the 2Dmap of the depth of the ablated tissue is repeated multiple times alonga perpendicular line across the width of the lesion site each of the 2Dmap of depth being parallel to the line along the length of the lesionand integrating each of the respective 2D maps of depth of the ablatedtissue on the perpendicular line reconstructing a 3D image of the depthof the ablated tissue. In some embodiments, the illumination, imagingand producing are performed while a radio frequency, cryoablation orlaser catheter is used to ablate the tissue. In some embodiments, theillumination and imaging are performed using a fiber optic waveguidecoupled to a tip of the lumen catheter, the fiber optic waveguidedelivers ultraviolet light from the ultraviolet light source to theilluminated tissue. In some embodiments, the ablation is performed byusing one of a radio frequency catheter, cryo-ablation catheter, orlaser ablation catheter.

In some embodiments, a system comprises a catheter having a distal andproximal end to image ablated pulmonary vein and left atrial hearttissue and unablated gaps, comprising an inflatable compliant ornon-compliant balloon inflated with transparent fluid for displacingsurrounding blood to allow visualization of NADH fluorescence at thedistal end; an ultra-violet illumination device for illuminating thetissue at the distal end; and a micro fiberscope detecting theilluminated tissue at the distal end; a fluorescence camera at theproximal end for creating a 2D image, coupled to the fiberscope, thatincludes a filter that is configured to pass ultra-violet radiation fromthe illuminated tissue captured by the fiberscope; wherein the detected2D image shows the lesion site having a dark appearance due to lack offluorescence, gaps having a light appearance due to normal fluorescence,and any ischemic tissue having a brighter halo type appearancesurrounded the lesion site; an ablation device for ablating heart tissueat the distal end based on the detected 2D image; and a module fordetermining the depth of the lesion site along a line across the lengthof the lesion site by plotting the detected fluorescence intensity alongthe line, wherein a lowest fluorescence intensity measurementcorresponds to the deepest point of an lesion site and the highestfluorescence corresponds to unablated tissue. In some embodiments, themodule applies a pixel gray scale ranging from completely black tocompletely white, where 0 is completely black and is the deepest pointand 255 is completely white and is the shallowest point, providing 256(0-255) levels of gray, to create a 2D map of the depth of the lesionsite along the line. Wherein the 2D map of the depth of ablated tissueis an absolute measurement, with the fNADH signal intensity isnormalized to a previously established fNADH/depth grey value scale. Insome embodiments, the 2D map of the depth of the ablated tissue isrepeated multiple times along a perpendicular line across the width ofthe lesion site each of the 2D map of depth being parallel to the linealong the length of the lesion and integrating each of the respective 2Dmaps of depth of the ablated tissue on the perpendicular linereconstructing a 3D image of the depth of the ablated tissue. In someembodiments, a display coupled to the external camera illustrates thedetected 2D image. In some embodiments, the ablation device is anablation catheter having a proximal and distal end. In some embodiments,the ablation catheter is a laser delivery catheter, a radio-frequencydelivery catheter, or a cryo-ablation catheter.

In some embodiments, a catheter to image ablated epicardial heart muscletissue and unablated gaps, having a proximal and distal end comprises anultra-violet illumination device for exciting mitochondrial NADH of theepicardial heart muscle tissue; a fiberscope detecting NADH fluorescencefrom the illuminated epicardial heart tissue at the distal end; afluorescence camera at the proximal end for creating an image from thedetected NADH fluorescence, coupled to the fiberscope, that includes a460 nm band-pass filter to detect the NADH fluorescence captured by thefiberscope; wherein the detected 2D image shows the lesion site having adark appearance due to lack of fluorescence, gaps having a lightappearance due to normal fluorescence, and any ischemic tissue having abrighter halo type appearance surrounded the lesion site, a module fordetermining the depth of the lesion site along a line across the lengthof the lesion site by plotting the detected and measured fluorescenceintensity along the line; wherein a lowest fluorescence intensitymeasurement corresponds to the deepest point of an lesion site and thehighest fluorescence corresponds to unablated tissue. In someembodiments, the module applies a pixel gray scale ranging fromcompletely black to completely white, where 0 is completely black and isthe deepest point and 255 is completely white and is the shallowestpoint, providing 256 (0-255) levels of gray, to create a 2D map of thedepth of the lesion site along the line. Wherein the 2D map of the depthof ablated tissue is an absolute measurement, with the fNADH signalintensity is normalized to a previously established fNADH/depth greyvalue scale. In some embodiments, the 2D map of the depth of the ablatedtissue is repeated on a perpendicular line across the width of thelesion site parallel to the line along the length of the lesion andintegrating each of the respective depths of the ablated tissue on theperpendicular line reconstructing a 3D image of the depth of the ablatedtissue.

In some embodiments, a catheter having a proximal and distal end toimage ablated epicardial heart muscle tissue and unablated gaps,comprises an ultra-violet illumination device for exciting mitochondrialNADH of the epicardial heart muscle tissue at the distal end; afluorescence camera at the distal end that includes a 460 nm band-passfilter to detect the NADH fluorescence from the illuminated epicardialheart muscle tissue for creating an image from the detected NADHfluorescence; wherein the detected fluorescence data shows thephysiology of the lesion site having a dark appearance due to lack offluorescence, gaps having a light appearance due to normal fluorescence,and any ischemic tissue having a brighter halo type appearancesurrounded the lesion site; and a module for determining the depth ofthe lesion site along a line across the length of the lesion site byplotting the detected and measured fluorescence intensity along theline; wherein a lowest fluorescence intensity measurement corresponds tothe deepest point of an lesion site and the highest fluorescencecorresponds to unablated tissue. In some embodiments, the module appliesa pixel gray scale ranging from completely black to completely white,where 0 is completely black and is the deepest point and 255 iscompletely white and is the shallowest point, providing 256 (0-255)levels of gray, to create a 2D map of the depth of the lesion site alongthe line. Wherein the 2D map of the depth of ablated tissue is anabsolute measurement, with the fNADH signal intensity is normalized to apreviously established fNADH/depth grey value scale. In someembodiments, the 2D map of the depth of the ablated tissue is repeatedon a perpendicular line across the width of the lesion site parallel tothe line along the length of the lesion and integrating each of therespective depths of the ablated tissue on the perpendicular linereconstructing a 3D image of the depth of the ablated tissue.

As noted above, the present systems and methods provide for high qualityand verifiable lesions, which can be at least one aspect to the successof the ablation procedure and avoidance of recurrence. Quality lesionsmay be of adequate depth and cause cell necrosis completely from theendocardial surface to the epicardial surface of the heart (i.e.transmural) while minimizing damage to the non-cardiac structuresbeyond. The presently disclosed systems and methods provide feedback asto the extent of cell injury caused by the ablation and actually verifythe integrity of a lesion. The presently disclosed embodiments overcomeat least some of the problems of known technologies by addressing thelack of lesion-quality feedback by providing lesion visualization aswell as depth-of-lesion information to the physician at the time of theprocedure. This information should prove useful in forming and verifyingproper lesions, reduce fluoroscopy time, and reduce the rate ofarrhythmia occurrence, thereby improving outcomes and reducing costs.

According to embodiments, systems and methods of the present disclosureprovide real-time, direct visualization of lesions during ablation andgaps using NADH fluorescence. The presently disclosed systems andmethods work by detecting the contrast in fluorescence betweennon-viable ablated and viable myocardium. The present disclosureprovides depth-of-lesion information to the physician at real-time, atthe time of the procedure.

According to some aspects of the present disclosure, the disclosedsystems and methods can be used to determine lesion depth based on thepixel intensity obtained after ablating the tissue and imaging thetissue with a fNADH system. The assessment of ablated lesion depth canbe provided by correlating the image intensity provided by the fNADHsystem to the lesion depth. Which means, the correlated depth data canbe integrated into a 3D reconstruction of the lesion(s) giving thephysician timely feedback about lesion geometry and quality.

According to some aspects of the present disclosure, there is provide amethod for determining a depth of a lesion site that includesilluminating a heart tissue having a lesion site; obtaining amitochondrial nicotinamide adenine dinucleotide hydrogen (NADH)fluorescence intensity from the illuminated heart tissue along a firstline across the lesion site; creating a 2-dimensional (2D) map of thedepth of the lesion site along the first line based on the NADHfluorescence intensity; and determining a depth of the lesion site at aselected point along the first line from the 2D map, wherein a lowerNADH fluorescence intensity corresponds to a greater depth in the lesionsite and a higher NADH fluorescence intensity corresponds to anunablated tissue.

In some embodiments, the method further comprises forming the lesionsite in the heart tissue by ablation. The step of obtaining may comprisedetecting the NADH fluorescence from the illuminated tissue; creating adigital image of the lesion site from the NADH fluorescence, the digitalimage comprising a plurality of pixels; and determining a NADHfluorescence intensity of the plurality of pixels along the line acrossthe lesion site. In some embodiments, the method may further includedistinguishing the lesion site and a healthy tissue in the digital imagebased on an amount of the NADH fluorescence from the lesion site and thehealthy tissue; normalizing the digital image based on the NADHfluorescence intensity of pixels representative of the healthy tissue.

In some embodiments, the step of detecting comprises filtering the NADHfluorescence through a bandpass filter of between about 435 nm and 485nm. In some embodiments, the healthy tissue has a lighter appearance andthe lesion site has a darker appearance. The step of creating maycomprise plotting the NADH fluorescence intensity along the line acrossthe lesion site to create the 2D map of depth of the lesion site.

In some embodiments, the method further includes obtaining a NADHfluorescence intensity from the illuminated heart tissue along a secondline across the lesion site; creating a 2D map of the depth of thelesion site along the second line based on the NADH fluorescenceintensity; constructing a 3-dimensional (3D) image of the lesion sitefrom the 2D map along the first line and the 2D map along the secondline. In some embodiments, the steps of obtaining, creating anddetermining may be repeated multiple times along a perpendicular lineacross a width of the lesion site, each of the 2D maps of the depthbeing parallel to the first line along the length of the lesion site;and integrating each of the respective 2D maps of the depth of thelesion site on a perpendicular line to reconstruct a 3D image of thedepth of the lesion site.

The step of determining may comprise applying a pixel gray scale rangingfrom completely black to completely white. The method may be used toanalyze epicardial tissue, endocardial tissue, atrial tissue, andventricular tissue.

In some embodiments, the illuminating step comprises illuminating theheart tissue with a laser generated UV light, wherein the lasergenerated UV light may have a wavelength of about 300 nm to about 400nm.

According to some aspects of the present disclosure, there is provided asystem for imaging heart tissue that includes an illumination deviceconfigured to illuminate a tissue having a lesion site to excitemitochondrial nicotinamide adenine dinucleotide hydrogen (NADH) in thetissue; an imaging device configured to detect NADH fluorescence fromthe illuminated tissue; and a controller in communication with theimaging device, the controller being programmed to obtain a NADHfluorescence intensity from the illuminated tissue along a first lineacross the lesion site; create a 2-dimensional (2D) map of the depth ofthe lesion site along the first line based on the NADH fluorescenceintensity; and determine a depth of the lesion site at a selected pointalong the first line from the 2D map, wherein a lower NADH fluorescenceintensity corresponds to a greater depth in the lesion site and a higherNADH fluorescence intensity corresponds to an unablated tissue.

According to some aspects of the present disclosure, there is provided asystem for imaging heart tissue that includes a catheter having a distalregion and a proximal region; a light source; an optical fiber extendingfrom the light source to the distal region of the catheter to illuminatea tissue having a lesion site in proximity to the distal end of thecatheter to excite mitochondrial nicotinamide adenine dinucleotidehydrogen (NADH) in the tissue; an image bundle for detecting a NADHfluorescence from the illuminated tissue; a camera connected to theimage bundle, the camera being configured to receive the NADHfluorescence from the illuminated tissue and to generate a digital imageof the illuminated tissue, the digital image comprising a plurality ofpixels; and a controller in communication with the camera, thecontroller being configured to determine, from the digital image, a NAHDfluorescence intensity of the plurality of pixels along a first lineacross the lesion site, create a 2D map of a depth of the lesion sitealong the first line based on the NADH fluorescence intensity, anddetermine a depth of the lesion site at a selected point along the firstline from the 2D map, wherein a lower NADH fluorescence intensitycorresponds to a greater depth in the lesion site and a higher NADHfluorescence intensity corresponds to an unablated tissue

Systems, catheter and methods for treating Atrial Fibrillation (AF) areprovided. The fluorescence of endogenous NADH (fNADH) in heart tissue isimaged to identify ablated and unablated areas using a balloon guidedcatheter equipped with UV illumination source and UV capable fiber, afluorescence capable camera coupled to an imaging bundle and opticalband pass filter to detect NADH fluorescence. Gaps between ablated areascan be identified using the fNADH imaging and the gaps can then beablated. Depth of ablated lesions are predicted using a gray scaledisplay of the fNADH image and additional lesions can be delivered atlesions of inadequate depth. The imaging can be performed during theablation procedure and does not require additional chemicals, such ascontrast agents, tracers or dyes.

The foregoing disclosure has been set forth merely to illustrate variousnon-limiting embodiments of the present disclosure and is not intendedto be limiting. Since modifications of the disclosed embodimentsincorporating the spirit and substance of the disclosure may occur topersons skilled in the art, the presently disclosed embodiments shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

1-23. (canceled)
 24. A system for imaging tissue comprising: anillumination device configured to illuminate a tissue having a lesionsite comprising one or more lesions to excite mitochondrial nicotinamideadenine dinucleotide hydrogen (NADH) in the tissue; an imaging deviceconfigured to detect NADH fluorescence from the illuminated tissue; anda controller in communication with the imaging device, the controllerbeing programmed to receive data indicative of intensity of amitochondrial nicotinamide adenine dinucleotide hydrogen (NADH)fluorescence from the illuminated tissue having the lesion site; createa digital image of the lesion site from the detected intensity of NADHfluorescence of the lesion site, the digital image comprisinginformation about a depth of the one or more lesions; analyze thedigital image of the detected intensity of NADH fluorescence of thelesion site to extract the information about the depth of the one ormore lesions of the lesion site by creating a plurality of 2-dimensional(2D) maps of the depth of the one or more lesions of the lesion sitealong a plurality of lines across the digital image of the lesion sitebased on the detected NADH fluorescence intensity; and construct a3-dimensional (3D) image of the lesion site from the plurality of 2Dmaps such that the 3D image is representative of the depth of the one ormore lesions of the lesion site.
 25. The system of claim 24, wherein thetissue is a heart tissue.
 26. The system of claim 24, wherein the tissueis selected form the group consisting of epicardial tissue, endocardialtissue, atrial tissue, and ventricular tissue.
 27. The system of claim24, wherein the illumination device is a UV laser.
 28. The system ofclaim 24, wherein the imaging device comprises a camera and a fiberscopeextending from the camera to the tissue being illuminated.
 29. Thesystem of claim 24, wherein the imaging device further incudes abandpass filter of between 435 nm and 485 nm disposed between a cameraand a fiberscope.
 30. The system of claim 24, wherein the lesion sitecomprises two or more lesions and at least one interlesion gap, and the3D image illustrates the depth of the two or more lesions and of the atleast one interlesion gap.
 31. The system of claim 24, furthercomprising a catheter having a distal end configured to be positionedadjacent to the lesion site having one or more lesions in a tissue,wherein the catheter includes one or more optical fibers such that adistal end of the one or more optical fibers extends to the distal endof the catheter.
 32. A system for imaging tissue comprising: acontroller in communication with an imaging device, the controller beingprogrammed to receive data indicative of an intensity of NADHfluorescence from illuminated tissue, the illuminated tissue including alesion site, create a digital image of the lesion site from the NADHfluorescence intensity of the lesion site, wherein the digital imagecomprises information about a depth of one or more lesions of the lesionsite; analyze the digital image of detected intensity of NADHfluorescence of the lesion site to extract the information about thedepth of the one or more lesions of the lesion site by creating aplurality of 2-dimensional (2D) maps of the depth of the one or morelesions of the lesion site along a plurality of lines across the digitalimage of the lesion site based on the detected NADH fluorescenceintensity; and construct a 3-dimensional (3D) image of the depth of theone or more lesions of the lesion site in the digital image from theplurality of 2D maps along the plurality of lines; and a displayconfigured to display the 3D image of the depth of the one or morelesions of the lesion site.
 33. The system of claim 32, wherein thelesion site comprises two or more lesions and at least one interlesiongap, and the 3D image illustrates the depth of the two or more lesionsand of the at least one interlesion gap.
 34. A method for operating asystem for determining a depth of a lesion site, the method comprising:by a controller, receiving data indicative of intensity of amitochondrial nicotinamide adenine dinucleotide hydrogen (NADH)fluorescence from an illuminated tissue having a lesion site comprisingone or more lesions; by the controller, creating a digital image of thelesion site from detected intensity of NADH fluorescence of the lesionsite, the digital image comprising information about a depth of the oneor more lesions; by the controller, analyzing the digital image of thedetected intensity of NADH fluorescence of the lesion site to extractthe information about the depth of the lesion site by creating aplurality of 2-dimensional (2D) maps of the depth of the one or morelesions of the lesion site along a plurality of lines across the digitalimage of the detected NADH fluorescence intensity of the lesion site; bythe controller, constructing a 3-dimensional (3D) image of the depth ofthe one or more lesions of the lesion site in the digital image from theplurality of 2D maps along the plurality of lines; and by thecontroller, causing the 3D image of the depth of the one or more lesionsof the lesion site to be displayed.
 35. The method of claim 34, whereinthe tissue is a heart tissue.
 36. The method of claim 34, wherein thetissue is selected form the group consisting of epicardial tissue,endocardial tissue, atrial tissue, and ventricular tissue.
 37. Themethod of claim 34, wherein the step of obtaining comprises obtainingthe NADH fluorescence from the tissue having the lesion site formed byan ablation device.
 38. The method of claim 34, further comprisingdistinguishing the lesion site and a healthy tissue in the digital imagebased on an amount of the NADH fluorescence from the lesion site and thehealthy tissue; and normalizing the digital image based on the NADHfluorescence intensity of pixels representative of the healthy tissue.39. The method of claim 38, wherein the healthy tissue has a lighterappearance and the lesion site has a darker appearance.
 40. The methodof claim 34, wherein the step of detecting comprises filtering the NADHfluorescence through a bandpass filter of between 435 nm and 485 nm. 41.The method of claim 34, wherein the step of creating comprises plottingthe NADH fluorescence intensity along the line across the lesion site tocreate the 2D map of depth of the lesion site.
 42. The method of claim34, further comprising an illuminating device for generating a UV light.43. The method of claim 42, wherein the UV light has a wavelength of 300nm to 400 nm.
 44. The method of claim 34, wherein the lesion sitecomprises two or more lesions and at least one interlesion gap, and the3D image illustrates the depth of the two or more lesions and of the atleast one interlesion gap.